The present invention relates to a waste solution treatment method and the apparatus therefor, and more particularly, to those suitable for treating waste solution discharged as a result of a development of a photographic light-sensitive material (photosensitive material) with an automatic developing machine, within an automatic developing machine or in the vicinity thereof.
Normally, in a photographic treatment of a silver halide photographic light-sensitive material, a monochrome light-sensitive material (black and white photosensitive material) is fixed, and water-washed and a color light-sensitive material (color photosensitive material) is color-developed, bleach-fixed (or bleached and fixed), water-washed, and stabilized.
In the photographic processing of a large quantity of light-sensitive materials, any component which has been consumed for a photographic processing is replenished. A component which has eluted as a result of the photographic processing or a component which has condensed as a result of evaporation (for example, bromide ions which exist in a developer and silver complex salts which exist in a fixing solution) are removed to maintain the content rate of each component of the processing solution to be constant, whereby the performance of the processing solution does not vary. In this photographic processing, a replenisher is supplied with the processing solution and part of the processing solution is wasted to remove the concentrated component.
In recent years, the amount of a processing solution as well as water is reduced to a great extent in carrying out a photographic processing in order not to cause environmental pollution and to carry out a photographic development at a low cost.
In automatic developing machines, a waste solution of a photographic processing is fed from a treating tank to a waste solution pipe where the waste solution is diluted with a coolant provided with the automatic developing machine, and then, wasted in sewerages.
According to Water Pollution Control Law and prefectural ordinances recently put into force, it is permitted to waste water and coolants used for photographic processings to sewerages and rivers, however, it is not permitted to waste photographic waste solutions such as a developer, fixing solution, color developer, bleach-fix solution (or bleaching solution and fixing solution), and stabilizing agent to sewerages and rivers. Following methods for reducing pollution load caused by photographic processing waste solutions are known: Activated sludge method (disclosed in Japanese Patent Laying-Open Publication Nos. 7952/1976 and 12943/1976); evaporation method (disclosed in Japanese Patent Laying-Open Publication No. 89437/1974 and Japanese Patent Examined Publication No. 33996/1981); electrolytic oxidation method (disclosed in Japanese Patent Laying-Open Publication Nos. 84462/1973, 119457/1974, 119458/1974, and Japanese Patent Examined Publication No. 43478/1978); ion exchange method (disclosed in Japanese Patent Examined Publication Nos 37704/1976 and 43271/1978, and Japanese Patent Laying-Open Publication No. 383/1978); reverse osmosis method (disclosed in Japanese Patent Laying Open Publication No. 22463/1975); chemical treating method (disclosed in Japanese Patent Laying-Open Nos. 64257/1974, 12152/1978, 58833/1974, 63763/1978, Japanese Patent Examined Publication Nos. 37395/1982, and 37396/1982). These methods, however, are not effective for reducing pollution load of photographic processing waste solutions.
An apparatus which facilitates a treatment of a photographic waste solution was proposed in Japanese Utility Model Laying-Open Publication No. 70841/1985. According to the disclosure, pressure is applied to a photographic waste solution so as to evaporate, and then, condense or solidify the photographic waste solution. When the photographic waste solution is evaporated, poisonous gases or gases having an offensive odor such as sulfur dioxide, hydrogen sulfide, ammonia gas are generated. This is because ammonium thiosulfate and sulfites (ammonium salts, sodium salts and potassium salts) contained in a photographic solutions such as a fixing solution and a bleach-fix solution are decomposed at a high temperature. In addition to the gas generation, the pressure in an evaporation oven increases owing to the cubical expansion caused by the aerification of water which is contained in photographic waste solution when an evaporation treatment is carried out. As a result, the above-described poisonous gases or gases having an offensive odor leak from a waste solution treatment apparatus.